Circuit-interrupting system.



LEV/IS W. CHU'BB, OF PITTSBURGH. PENNSYL ELECTRIC AND MANUFACTURING COMPANY, L CORORATION CIRCUIT-INTERRUPTING SYSTEM.

Application filed May 3,

lie it ltnovvzi that I, liilvvis Vil. CHUBB. a citizen ot the llnited States. and a resident ot' llittsl'iurgh. in the county of fillegrhenjv7 and State oi Pennsylvania, have invented a nevi' and useful iniln'ovenient iii Circuit-lip terrupting plans-tenisv` or ivhich the following is a specification.

Mv invention relates to circuit-interrupting svstenis and particularly to circuit interrupters that arx adapted to open at the iiistant the instantaneous value ot the current traversing the saine is suhstantiall)v zero.

The object ote nrv invention to provide a circuit interrupter ot the above indicated character that shall have nieansl t'or energiziurY its trip coil a sutlicient time interval het'ore the instantaneous value ot' the current. having a predetermined niaxiinuni value. passes through zero to pei-init the circuit interriuiter to open ivhen the instantaneous value ot' the current is substantially zero.

lt is a riell known tact that. it a circuit interrupter is tripped when the instant-a ncous value ot the current traversing itis zero. no arcine' u'ill occur and a relativeij.' sinall interrupter ina)v he used, However. it a tapping' device is operated vvhen the 'current traversing' the circuit interrupter has a predeteruiined value. there is a likelihood that the interrupter ivill open when the in- Istantaneous value of the current is other than zero. ln vieiv ot this l connect a seriesresouantcircuit vto the main circuit and l connect a spark grap in circuit with a trip cnil. The trip-coil circuit is connected in shunt relation to the condensive portion oil the resonant circuit. and the phase-angular relation ot the. condensive portion is so shitted that its maximum voltage Will occur an interval oi' tinie betere the instantaneous 'alue ot the current that traverses the niain circuit passes through zero. This time interval is. oi" course. deterniined h'v the speed o oi'ieration ot the interrupter.

The single ligure ot' Jthe acconipan'vin nA drawing' is a diagrammatic vieu7 oi an electric circuit enihodvinfdr in;Y invention.

A generator l supplies current to a circuit Q coinikirisingg conductors 3 and Ll. .il circuit interrup'ter 5 is connected in circuit with the conduct'` r 3 oi'3 the circuit Q for the'purpose of opening the saine ivlieu the current reaches a. predetermined value. llrhile l Specification of Letters Patent.

VANIA, ASSIGNGR TG 'WESTINGHO'SE OF PENNSYLVANEA.

Patented tid, i918@ isis. serieiiioeaosa.

have shown a circuit interrupter as connected iii only one it will, of course7 conductors of the in the saine nianner.

conductor ot the circuit, toe understood that both circuit nia)Y be protected An impedance coil 6 having;l a relatively small impedance is the conductor 3, a

connected in circuit with nd a series-resonant circuit l, comprising a reactor 8, a condenser 9 and a variableI resistor 1'2, is connected in shunt relation to t trip coil 10 is conn a spark gap l1 an( t-uted. is connected condenser 9.

he impedance coil tl. ected in series relation to l the circuit. thus constiin shunt relation to the,

lf the impedance. coil 6 were entirelvY noiiinductive. the 9 would he in tional to, the ductor 3. hence. it

potential across quadrature with. and proporcurieiittraversing' the conthe condenser s niaxiniuni value would so set that it ivill hrealt dotvn 'when this determined niaxiin trip coil 10 ivill li cuit interrupter time after instantaneous valu ing the circuit 3 ni preuni value is reached, the e energized and the cirivill open. Hoiverer, since the circuit. iiiterrupter 5 operates a definite the trip coil is energized, the

e ot the current. traversav lie other than its zero value. when the circuit interruptcr 5 is trified.

l It the nnpedanc phase relation oi denser 9 ina;v he so e coil 6 is inductive, the the voltage of the conad anced that its inaniinuni 'value vv'll occur atinie interval before the. instantaneous zero value oit' the current the sliif that traterses phasemugular it corresponds circuit intcirupter to the tiine circuit 8. Thus, it this t is so proportioned that required for the 5 to operate. the circuit interrupter will open when the instantaneous value of the current zero. and. consequently.

ru pter 5 inajx adapted to he open current trave no disturbances ivill o time required rupter to operate. troni of current in its ti trarersing it is the circuit interJ loe relatively small and inea? pensive to construct.

Since the circuit Z is ed at the zero point. in its surges or other similar ccur.

for a circuit intertlie impulse or flow ip coil to the opening; or'

its contact nieinhers is substantially constant it the electric al impulse or How of current in the trip coil is always the same. Since the electrical impulse or current that traverses the trip coil 10 is the discharge of the condenser 9 ott definite capacitance which is charged to a voltage equal to the sparking potential ot' the definite spark gap ll, the time required for the interrupter to open is always the same.

It is a Well known fact that, upon sudden short circuits and overloads, it is desirable to open the circuit 2 only after the reactions in the generator l have reduced its field current and any unsymmetrical transient. in the circuit 2 has reached a symmetrical periodic value. Since the interrupter 5 is adapted to trip only after the resonant circuit 7 has stored suicient energy to raise the potential of the condenser 9 to the spark potential of the spark Oap 11,.-it is assured that the interrupter will not trip upon the first impulse of a sudden short circuit or overload.

The variable resistor 1Q is utilized for producing such a dull resonance in the circuit 7 that the interrupter 5 will not be tripped by the usual variations in the frequency of .the circuit. The resistor 12 may be used for adjusting the interrupter to trip at various values of overload and for manual trippino'. It the resistance of the resistor' 12 is decreased, an increased current will traverse the circuit 7 and the ratio of the potential otl the condenser 9 and the current that traverses the circuit may be varied without changing the value of the impulse or current that traverses the trip coil. i

lVhile have described my invention with respect to the tripping ot a circuit interrupter when the instantaneous value ot the current traversing it is substantially1 zero, do not limit my'inventionto tripping a circuit interrupter or to the particular instantaneous value at which it is to be tripped; Neither do I limit mv invention to the particular means tor shitting the phase-angular relation of the portions ot' the resonant circuit, as many .modifications and adaptations may be made in in v invention without departing from the spirit and scope of the same as set forth in' the appended claims.

i claim as my invention:

Lin ani-electric circuit, the combination with a circuit interruptor and a trip coil, of an impedance coil connected in series with the circuit, a series resonant circuit connectedv in shunt relation to the said impedance coil, and a spark gap connected in series with the trip coil, the circuit, thus constituted, being connected in shunt relation toa portion of the resonant circuit, said spark Zgap being adapted to break down when ay predetermined current traverses the circuit and a predetermined interval of time before the current wave passes through -its zero value.

current traversing the electric circuit' reaches its zcro'value.

3. ln an electric circuit, the combination with a circuit interrupter and a trip coil, ofa series-resonant circuit operatively connected to the electricV circuit, a spark gap operatively connected to the trip coil, the tripcoil circuit being connected tol the condensive portion ot' the resonant circuit, and means for so advancing the phase-angular relation of the condensive portion ot the resonant circuit that the spark gap will break down a sutlicient interval of time before the instantaneous value ot' the current traversing the electric circuit reaches its zero value to permit the circuit interrupter to be tripped when that condition obtains.

4. The c mbination with an alternating, current circuit, of means t'or producing an inductive-impedance drop therein, a series resonant circuit so connected that said drop is impressed thereon, an electrically oper ated circuit-interruptin-g device insaid alternating-current circuit, and means for operating said device in accordance with the voltage across one ot' the elements of said resonant circuit.

5. The combination with an alternating- -current circuit, ot means for producing an indilctive-impedance drop therein, a series resonant circuit comprising a condenser and an inductive reactor and so connected that said drop is impressed thereon, an electrically operated circuit-interrupting device in said alternating-current circuit, and means for operating said device in accordance with the voltage across said condenser.

G.V The combination With an alternatingcurrent circuit, of means for producing an, indnctive-impedance drop therein, a series resonant circuit so connected that said drop is impressed thereon, an electrically oper ated circuit-interrupting device in said alternatingcurrent circuit, means providing a spark-gap, and means for impressing the voltage across an element of said resonant circuit upon the operating Winding of said device through said spark-gap,

7. The combination with an alternating current circuit, of means for producing an inductive-impedance drop therein, a series resonant circuit comprising a condcnsive rcactor and an inductive reactor, means 'for so connecting said resonant circuit that said voltage drop is impressed thereupon, an electrically operated circuit-interrupting device in said alternating-eurrent circuit, means providing a spark-gap, and means for applying 'the voltage across said eondensive reactor to the operating coil of said device through said spark-gap.

8. The combination with an alternatingcurrent circuit, of means for producing a voltage drop therein, a series resonant circuit including a damping resistor so connected that said .drop is impressed thereon, an electrically operated circuit-interrupting device in said and means for operating said device in accordance with the voltage cross one of' the elements of said resonant circuit.

Q iflhe combination with an alternatingcurrent circuit; otmeans for producinga voltage drop therein, a series resonant circuit comprising a condenser, an inductive reactor and a damping resistor so connected that said drop is impressed thereon, an electric-all)Y operated circuitinterrupting de vice in said alternating-current circuit, and` means for operating said device in accordance with the voltage across said condenser.

10. The combination with van alternatingcurrent circuit, of an electrically-tripped cireuit'-interrupting device inserted therein and requiring a predetermined period ot' time for its operation after-'initial energiza tion, means for deriving an alternating electroniotive force from said circuit substantially proportional yto the load-current l'ow in said circuit and having a. maximum value at substantially said period of time prior to each instant of zero current flow in said alternating-current circuit,

circuit, and means for supplying an operating impulse from said derived electroniotive force to the tripping mechanism of said interrupting device at each crest of said derived electromotive force when the derived electromotive force exceeds va predetermined value, whereby said device is caused to interrupt said circuit at or near times of zero current flow.

1l. The combination with an alternatingcurrent circuit, of an electrically-tripped circuit-interruptingv device inserted therein and requiring a predetermined period of timefor its operation after initial energization, means for `deriving an alternating electromotive force from said circuit substantially proportional .to the load-current flow in said circuit and having a maximum value at substantially saidperiod of time prior to each instant of zero current ow in said eircuit, and a circuit including a spark-gap for supplying an operating' impulse from said derived electromotive torce to the tripping mechanism of said interrupting device when said electroinotive force exceeds a predetermined amount, the set-ting of said spark-gap being such as to permit the tlow of tripping current only at the crests ot' the derived electromotive torce waves attendant upon the flow of abnormal current in said alternatingcurrentcircuit, whereby said device is caused to interrupt said alternating-eurrent circuit at or near a point ot zero current flow therein.

In testimony whereof, l have hereunto subscribed in v name this 28th day ot' A\pril, 1916.

LEWIS lV. CI-lUBl. 

